BAGGING AND PALLETIZING SYSTEM PROVIDES KEY TO COMPANY’S SUCCESS

An animal feed manufacturer installs an integrated turnkey bagging and palletizing system for a new production line.

Novus International Inc., headquartered in St. Charles, Mo., is a global supplier of animal feed ingredients and other products for poultry, cattle, pigs, horses, pets, and other animals. The company’s Novus Arkansas LLC facility in Little Rock, Ark., produces and exports proprietary animal feed ingredients to more than 70 countries around the world. In 2009, the company expanded the Little Rock facility to boost production to meet increasing customer demand. To ensure that the various products were properly packaged, palletized, and secured for transport, the com­pany needed to find a fast, reliable, and accurate automated bagging and palletizing system.

Finding a turnkey system

When searching for the bagging and palletizing system, the company sent all of the performance requirements and requested quotes from the leading packaging system suppliers in North America. The company needed to accurately fill 25-kilogram pinch-bottom open-mouth bags at 14 bags per minute and 1,000-kilogram open-valve woven polypropylene bulk bags at 12 bags per hour. The 25 kilogram bagger and palletizer also had to be able to handle three different bag types: multi-walled paper bags, plastic-lined paper bags, and low-density polyethylene plastic bags. Additionally, the company needed to ensure that the palletized bags were secure and protected from the elements during transport.

“We wanted a complete automated turnkey system with all of the components coming from one supplier,” says Kevin Mowery, Novus senior director of operations and supply chain. “As we went through the bid evaluation process, we found one particular supplier that listened well to our requirements and was very professional in their business and techni­cal approach. We did reference checks on similar equipment that they’ve installed, and their customers were very satisfied, not only with the equipment but with the follow-up technical support. Additionally, some of our team members had had positive experiences working with the supplier in the past on other projects with other companies.”

Since the company’s products are composed of small, free-flowing granu­lar particles with a wide range of sizes, the company sent several different product samples along with the three bag types to the supplier for testing.

Novus team members traveled to the supplier’s facility to witness the tests, which proved the supplier could achieve the required bagging rates and accuracies.

“However, we wanted to make sure they could deliver the performance level we were looking for on a large scale, so we also went to a facility near their headquarters and one near our facility to see the system in operation,” says Mowery. “One thing we noticed right away is the robustness of their equipment’s design; it has very heavy-duty frames and members and an overall higher-quality look and feel to it than some of the other equipment we saw. Another thing we liked is the ability to use third-party replacement parts for off-the-shelf components, such as servo motors, because it minimizes production downtime and maintenance costs since we can get them faster at a lower price. We had a good feeling that the supplier’s integrated system would do the job and last a long time, so we decided to purchase one for our facility.”

The bagging and palletizing system

The new automated turnkey system consists of a feeder and scale, a single-spout open-mouth bagger, a belt conveyor, a high-level pallet­izer, a bulk bag filler, a powered roller conveyor, a stretch hooder, PLC controllers, and various ancillary equipment and sensors. The equipment arrived at the Little Rock facility in fall 2010, and the supplier sent several technicians to help the company install, commission, and check out the system. In November 2010, the company started the new automated system without any problems and began bagging and palletizing products that same day.

The integrated bagging and packaging system is programmed to allow the company to fill products into 25-kilogram bags and 1,000-kilogram bulk bags simultaneously, ensuring that the required production rates are always achieved. When filling 25-kilogram bags, the company conveys a product into a hopper installed above a model E-55GHS gravity high-speed feeder, which feeds the product from the hopper to a model E55-NXT electronic net weigher. The servo-driven feeder, which is controlled by the scale, starts gravity-feeding the product with its gate fully open. As the scale nears the set weight, the feeder’s gate slowly starts closing in harmonic motion with the increasing weighment so that the gate fully closes at the precise moment the target weight is achieved. According to Anthony Siblall, Premier Tech Chronos sales director, this feeding mode provides faster feedrates and more accurate weighments than typical bulk-dribble feeders can.

As the scale doses the product into the model PTK-1700 high speed automatic bagger, the bagger’s pickup unit lifts an empty bag from the empty-bag magazine, straightens and opens it, and places it onto the dust-tight filling spout. The product then discharges by gravity from the scale through the spout into the open bag. An integral dust collection system removes the displaced air and dust from the bag for a dust-free bag-filling operation, and a settling device helps deaerate the product while the bag is being filled. The filled bag is transferred to an outfeed conveyor, which moves the upright bag through a bag-sealing system and an ink-jet printer for custom labeling.

From the printer, the bag moves through a bag kicker that lays it down flat onto a belt conveyor. The belt conveyor moves the bag through a leak detector, which signals a bag rejector to remove it from the line if a leak is detected. The bag is then conveyed to an inclined bag flattener that flattens and shapes it for palletizing. Next, the bag is moved over a checkweigher and through a metal detector with an ink-code marker to a short gravity conveyor with a bag rejector. If a bag is outside the preset accuracy range, the checkweigher signals the bag rejector to remove it from the line. If metal is detected in a bag, the metal detector marks it and the rejector removes it from the line, allowing operators to easily differentiate the bags.

After moving down the gravity conveyor, the bag is moved to the model AP-425 high-level automatic bag palletizer, which has automatic empty-pallet and slip-sheet dispensers and can palletize up to 25 bags per minute in a 5-bag pattern. The palletizer’s standard overhead turning device turns and orients the bag in the appropriate preprogrammed pattern and places it on the pallet stack. When a bag layer is completed, the palletizer’s two-speed electric pallet elevator lowers so that the next successive bag layer can be completed. The palletizer alternates the stacking pattern of each layer to ensure pallet stability.

At the same time the open-mouth bagger is operating, the company can convey a product into a hopper installed above the model BG-931 automatic bulk bag filler. In operation, the bulk bag filler automati­cally places an empty pallet on the filler’s scale deck, which is directly below the hopper discharge. The scale deck is mounted on four load cells that communicate the bag weight to the filler’s PLC during filling. After the pallet is in position, the operator manually hangs an empty bag in the filler’s bag-holding frame and inserts a double-walled fill spout with an expander band into the bag’s open valve to create a dust-tight seal. When the product flows through the spout’s center tube into the bag, displaced air and dust are pulled through the spout’s outer tube by the dust collection system. After the operator activates the filler, a model E-55GHS gravity high-speed feeder feeds the product from the hopper into the bulk bag. A vibrator operates intermittently to help settle the product in the bag. When the bulk bag reaches the target weight, the operator releases the bag handles and removes the fill spout from the bag. The scale deck’s powered rollers then eject the completed pallet onto the powered roller conveyor that moves it to a checkweigher and then to the stretch hooder. If a bulk bag is outside the preset accuracy range, the system stops and an alarm sounds so that a forklift can remove the pallet from the line. To ensure a contaminant-free product, a metal detector installed in the product conveying line just before the hopper diverts any contaminated product out of the conveying line and shuts down the system to alert the operator.

The powered roller conveyor moves the completed pallets from both the palletizer and bulk bag filler to the same stretch hooder. Sensors installed on the conveyor provide traffic control, giving preference to pallets from the palletizer and allowing the company to work both lines at the same time. The stretch hooder places a film hood over the bags to secure the load to the pallet and keep out moisture. The film hood exerts vertical and horizontal tension on the load, gently pressing it down onto the pallet to improve the packaging quality of unstable or heavy loads. From the stretch hooder, the pallets move through a four-sided labeling machine, which applies a label to the sides of the film hood, and then onto an indexing conveyor, where they wait for a forklift to move them to the warehouse.

The bagging and palletizing system uses five PLC controllers: one each for the bagger, palletizer, stretch hooder, bulk bag filler, and traffic control sensors. The bagger’s PLC is integrated with the palletizer’s PLC, allowing operators to make parameter changes to both at the bagger. All of the other equipment’s operating parameters are made individually at the associated PLC. To ensure safe operation, light curtains are installed at strategic locations throughout the system where human entry is considered unsafe. If a light curtain is broken or interrupted, such as by an operator’s arm or flying debris, the system automatically shuts down.

Fast and accurate bag filling

Since installing the bagging and palletizing system, the company has been filling bags at the required rates with accuracies of ±56 grams at 2 Sigma for the 25-kilogram bags and ±454 grams at 2 Sigma for the 1,000-kilogram bulk bags. “The bagger’s ability to handle different bag types allows us to give customers exactly what they want,” says Mowery. “The palletizer does a good job of squaring up the bags and making a nice-looking pallet with neatly stacked bags. And we like the stretch hooder’s design and how well it functions. Because its one-piece film hood fits over the bags and pallet to secure the load, it produces a more stable and better weather-proofed pallet during transport than a stretch-wrapper can. That’s important for us because we export a lot of the products overseas in containers, and we want the pallets and products to be intact and undamaged when they reach the customer.”

According to Mowery, the supplier delivered a cost-effective, efficient, and reliable turnkey bagging and packaging system. “It’s completely integrated, and they’ve taken responsibility for all of the equipment, even if they didn’t manufacture it, so there’s only one telephone number we need to call when we need service. The system provides dust-free, spill-free, accurate, and fast bag filling for us, and it’s user-friendly and cleans out easily between product runs. It was easy for our operators to learn how to use, and only one operator per shift is needed run the entire operation. The supplier has been responsive and knowledgeable and provides us with good support when we need it, which has minimized downtime and maximized production uptime.”